{"id":219252,"date":"2025-05-25T21:28:07","date_gmt":"2025-05-25T21:28:07","guid":{"rendered":"https:\/\/learnexams.com\/blog\/?p=219252"},"modified":"2025-05-25T21:28:09","modified_gmt":"2025-05-25T21:28:09","slug":"indicate-which-of-the-following-has-the-lowest-standard-molar-entropy","status":"publish","type":"post","link":"https:\/\/www.learnexams.com\/blog\/2025\/05\/25\/indicate-which-of-the-following-has-the-lowest-standard-molar-entropy\/","title":{"rendered":"\u00a0Indicate which of the following has the lowest standard molar entropy"},"content":{"rendered":"\n
    \n
  1. Indicate which of the following has the lowest standard molar entropy (S\u00ba)? a. CH4 (g) c. He (g) d. Na(s) b. CH3CH2OH(1) e. H2O(s) 11. Which of the following has the highest entropy at 298 K? a. 0.5 g of HCN b. 1 mol of HCN c. 2 kg of HCN d. 2 mol of HCN e. All of the above have the same entropy at 298 K 12. Predict the sign of the entropy change of a reaction (S positive or negative) a. Caco: (s) Cad(s) + CO2 (g) b. CS (1) CS, (g) c. 2 Hg (1) + O2(g) 2 HgQ (s) d. 2 Na,O2 (s) + 2 H2O (1) 4 NaOH(aq) + O2(g)<\/li>\n<\/ol>\n\n\n\n

    The Correct Answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n

    Answers:<\/strong><\/h3>\n\n\n\n

    10.<\/strong> The correct answer is d. Na(s)<\/strong>
    11.<\/strong> The correct answer is d. 2 mol of HCN<\/strong>
    12.<\/strong><\/p>\n\n\n\n

      \n
    • a. Positive (\u0394S > 0)<\/strong><\/li>\n\n\n\n
    • b. Positive (\u0394S > 0)<\/strong><\/li>\n\n\n\n
    • c. Negative (\u0394S < 0)<\/strong><\/li>\n\n\n\n
    • d. Positive (\u0394S > 0)<\/strong><\/li>\n<\/ul>\n\n\n\n
      \n\n\n\n

      Explanation <\/strong><\/h3>\n\n\n\n


      Standard molar entropy (S\u00ba) refers to the entropy content of one mole of a substance at standard conditions (298 K and 1 atm). Entropy generally increases from solids to liquids to gases. Among the options:<\/p>\n\n\n\n

        \n
      • CH\u2084(g)<\/strong>, He(g)<\/strong>: gases \u2192 high entropy<\/li>\n\n\n\n
      • CH\u2083CH\u2082OH(l)<\/strong>: liquid \u2192 moderate entropy<\/li>\n\n\n\n
      • H\u2082O(s)<\/strong>: solid \u2192 low entropy<\/li>\n\n\n\n
      • Na(s)<\/strong>: solid metal \u2192 lowest entropy<\/strong>, since metals are highly ordered in crystal form<\/li>\n<\/ul>\n\n\n\n

        Thus, Na(s)<\/strong> has the lowest<\/strong> standard molar entropy.<\/p>\n\n\n\n

        Question 11:<\/strong>
        Entropy depends on amount (moles)<\/strong>, not mass alone. While all options refer to HCN, they differ in quantity:<\/p>\n\n\n\n

          \n
        • 0.5 g<\/strong> and 2 kg<\/strong> of HCN are masses, but entropy is extensive\u2014it increases with the number of particles.<\/li>\n\n\n\n
        • 1 mol<\/strong> vs. 2 mol<\/strong>: more moles = more microstates = higher entropy.<\/li>\n<\/ul>\n\n\n\n

          So, 2 mol of HCN (d)<\/strong> has the highest entropy<\/strong>.<\/p>\n\n\n\n

          Question 12:<\/strong>
          Entropy change (\u0394S) depends on the change in disorder<\/strong> during a reaction:<\/p>\n\n\n\n

            \n
          • a. CaCO\u2083(s) \u2192 CaO(s) + CO\u2082(g):<\/strong> A gas forms from solids \u2192 \u0394S > 0 (positive)<\/strong><\/li>\n\n\n\n
          • b. CS\u2082(l) \u2192 CS\u2082(g):<\/strong> Liquid to gas = more disorder \u2192 \u0394S > 0 (positive)<\/strong><\/li>\n\n\n\n
          • c. 2 Hg(l) + O\u2082(g) \u2192 2 HgO(s):<\/strong> Liquids and gas forming solid = decrease in entropy \u2192 \u0394S < 0 (negative)<\/strong><\/li>\n\n\n\n
          • d. 2 Na\u2082O\u2082(s) + 2 H\u2082O(l) \u2192 4 NaOH(aq) + O\u2082(g):<\/strong> More particles, especially gas and aqueous ions formed = more disorder \u2192 \u0394S > 0 (positive)<\/strong><\/li>\n<\/ul>\n\n\n\n

            In summary, entropy is influenced by phase, number of particles, and state changes<\/strong>. Gases and more moles usually mean higher entropy<\/strong>.<\/p>\n\n\n\n

            \"\"<\/figure>\n","protected":false},"excerpt":{"rendered":"

            The Correct Answer and Explanation is: Answers: 10. The correct answer is d. Na(s)11. The correct answer is d. 2 mol of HCN12. Explanation Standard molar entropy (S\u00ba) refers to the entropy content of one mole of a substance at standard conditions (298 K and 1 atm). Entropy generally increases from solids to liquids to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-219252","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/219252","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=219252"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/219252\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=219252"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=219252"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=219252"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}